Electrical switches

ABSTRACT

An electrical switch has a casing with a plunger axially and angularly movable within the casing. Within the casing is a rotor coupled to the plunger for angular movement therewith, and a fixed contact is carried by the casing and engaged with the rotor. Abutment means is provided on the casing engageable by the rotor, to permit angular movement of the rotor but resist axial movement of the rotor during axial movement of the plunger.

United States Patent.

[72] Inventor Derek Rushton 21 Lime Road, Aeerington, Lancashire, England 21 Appl. No. 46,603 [22] Filed June 16, 1970 [45] Patented Jan. 4, 1972 [32] Priority July 7, 1969 [3 3] Great Britain [3 1 1 34,130/ 69 [54] ELECTRICAL SWITCHES 5 Claims, 4 Drawing Figs.

[52] US. Cl 200/16 C, 338/200 [51] Int. Cl ..1-I01h 15/00 [50] Field of Search 200/4, 11, 16 R, 156, 166 PC, 16 C; 338/200 [5 6] References Cited UNITED STATES PATENTS 2,512,788 6/1950 Brown et al 200/16 Primary Examiner-J. R. Scott Attorneyl-lolman & Stern ABSTRACT: An electrical switch has a casing with a plunger axially and angularly movable within the casing. Within the casing is a rotor coupled to the plunger for angular movement therewith, and a fixed contact is carried by the casing and engaged with the rotor. Abutment means is provided on the easing engageable by the rotor, to pennit angular movement of the rotor but resist axial movement of the rotor during axial movement of the plunger.

PATENTEDJAN 4:912 1632.910

- lNVENTOR PM Rub 5!? ATfi NEYS ELECTRICAL SWITCHES 2 This invention relates to electrical switches.

A switch according to the invention relates a casing a plunger, mounted for axial and angular movement within the casing, a rotor mounted for rotation within he casing and coupled to the plunger for angular movement therewith, a contact carrier by the casing and engaged with the rotor, and abutment means on the casing and engageable by the rotor, said abutment means permitting said angular movement of the rotor, but resisting axial movement of the rotor during axial movement of the plunger. One example of the invention is illustrated in the accompanying drawing wherein:

FIG. 1 is a sectional view of an electrical switch,

FIG. 2 is a fragmentary sectional view on the line 2-2 in FIG. 1, with parts thereof omitted for clarity, and

FIG. 3 is fragmentary sectional view on the line 33 in FIG. 1, also with parts thereof omitted for clarity;

FIG. 4 shows an exemplary view of the arrangement of a resistive electrically conductive path on a printed circuit board included in the electrical switch.

Referring to the drawings, the switch includes a moulded synthetic resin casing 11 inthe form of a rectangular box one side of which is closed by a first printed circuit board 12 engaged as a snap fit with the remainder of the casing 11. One of the end walls of the casing 11 includes an integral boss 13 within which is joumaled a plunger 14. The plunger 14 extends through the boss 13 into the casing 11, and is mounted in the casing 11 for a both axial and angular movement. Within the casing 11 the plunger 14 is of hexagonal cross section and the casing 11 includes an internal, integral support 15 which engages the plunger 24 intermediate its ends.

Slidably mounted within the casing 11 is a molded synthetic resin slider 16 carrying a contact plate 17 which is spring urged into engagement of exposed conductive areas on its inner surface which constitute fixed contacts 18 engageable by the contact plate 17, each of the contacts 18 being electrically connected to a respective external terminal blade. The innermost end of the plunger 14 is coupled to the slider 16 so that axial movement of the plunger 14 relative to the casing causes sliding movement of the contact plate 17 relative to the fixed contacts 18. The connection between the plunger 14 and the slider 16 is such that the plunger 14 can be rotated relative to the slider 16. The inner surfaces of the sidewalls 11a, 11b, of the casing 11 are formed with respective longitudinally extending cam tracks 19 engaged by balls 21 carried by the slider 16. The balls 21 are urged by springs into engagement with the cam tracks 19, and the cam tracks 19 and the balls 21 define detent means for retaining the slider 16, and therefore the contact piece 17 in any one of a plurality of axially spaced positions relative to the contacts 18.

Housed within the casing 11 adjacent the boss 13 is a rotor in the form of a second, circular printed circuit board 22, the conductive pattern of which defines a resistor. The printed circuit board 22 is formed with a central hexagonal hole 23 through which the plunger 14 extends, the arrangement being such that rotation of the plunger 14 causes rotation of the printed circuit board 22 relative to the casing 11. Engaged with the conductive pattern on the printed circuit board 22 are a pair of resilient wiping contacts 24 each of which is secured to the base 12, and is electrically connected to a respective external terminal. The contacts 24 together with the conductive pattern on the printed circuit board define a variable resistor, the resistance in circuit between the contacts 24 being dependent upon the angular position of the printed circuit board 22 relative to the contacts 24. A portion of the periphery of the printed circuit board 22 is formed with a pair of radially extending depressions 25, 26 either of which is engageable by a spring member 27 secured to the casing 11, the spring member 27 and the depressions 25, 26 constituting detent means defining a pair of stable positions of the printed circuit board 22 relative to the casing 11.

ln order to prevent axial movement of the printed circuit board 22 relative to the casing 11 when the plunger 14 is moved axially to move the slider 16, the casing is formed with a pan of internal, integral-abutments 28 which extend between the board 12 and the opposite wall of the casing 11, and which are engageable with one face of the board 22, the other face of the board 22 being engageable with the inner surface of the boss 13. The printed circuit board 22 is engaged between the abutments 28 and the boss 13 during assembly of the switch, prior to the insertion of the plunger 14 and the board 12.

lf'desired, the portion of the plunger 14 which is exposed as the spindle is moved axially relative to the casing! I, can he encased in a molded sheath 29 of a similar color to an operating knob (not shown) secured to the extreme outer end of the plunger 14.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electrical switch including a casing, a plunger mounted for axial and angular movement within the casing, a rotor mounted for rotation within the casing, movable contacts carried by the rotor, means coupling the rotor to the plunger for angular movement with the plunger relative to the casing, a fixed contact carried by the casing, and engaging the rotor, abutment means on the casing engaging the rotor, the abutment means permitting said angular movement of the rotor but resisting axial movement of the rotor during axial movement of the plunger, a slider mounted for sliding movement within the casing, a movable contact carried by the slider, further fixed contacts carried by the casing and engageable by said movable contact carried by the slider, and means coupling the slider to the plunger so that axial movement of the plunger causes sliding movement of said movable contact relative to said further fixed contacts.

2. A switch as claimed in claim 1 wherein said rotor includes a resistive electrical path which is engageable by said fixed contact, said fixed contact and said resistive path being electrically connected to respective terminals on the casing and the angular position of the rotor relative to the fixed contact determining the resistance of the electrical circuit between the terminals.

3. A switch as claimed in claim 1 wherein said abutment means is defined by an end wall of the casing and at least one flange integral withthe casing and extending within the casing in space relation to said end wall, the rotor being disposed between the end wall and the flange.

4. An electrical switch comprising a hollow casing, a plurality of fixed contacts mounted on the inner surface of the easing, a slider mounted for sliding movement within the casing and including a movable contact engageable with said fixed contacts, a plunger of noncircular cross section extending into the casing and joumaled in an end wall of the casing for axial and angular movement relative to the casing the inner end of the plunger being rotatably coupled to said slider so that axial movement of the plunger causes sliding movement of the slider relative to the fixed contacts, a pair of abutments positioned within the casing adjacent said end wall, a printed circuit board positioned between the end wall and said abutments, said plunger extending through a corresponding noncircular hole in the printed circuit board so that said printed circuit board is rotated by angular movement of the plunger, said end wall and said abutments preventing axial movement of the printed circuit board with the plunger, a resistive electrically conductive path on said printed circuit board, a wiping contact carried by the casing and engaged with said resistive path, and a pair of terminals on the casing, one of said terminals being electrically connected to one end of said resistive path and the other terminal being electrically connected to said wiping contact so that the resistance of the electrical contact between said terminals is dependent upon the angular position of the printed circuit board relative to the wiping contact.

5. A switch as claimed in claim 4 including resilient means for locating the printed circuit board in anyone of a plurality of predetermined angular positions relative to the casing. 

1. An electrical switch including a casing, a plunger mounted for axial and angular movement within the casing, a rotor mounted for rotation within the casing, movable contacts carried by the rotor, means coupling the rotor to the plunger for angular movement with the plunger relative to the casing, a fixed contact carried by the casing, and engaging the rotor, abutment means on the casing engaging the rotor, the abutment means permitting said angular movement of the rotor but resisting axial movement of the rotor during axial movement of the plunger, a slider mounted for sliding movement within the casing, a movable contact carried by the slider, further fixed contacts carried by the casing and engageable by said movable contact carried by the slider, and means coupling the slider to the plunger so that axial movement of the plunger causes sliding movement of said movable contact relative to said further fixed contacts.
 2. A switch as claimed in claim 1 wherein said rotor includes a resistive electrical path which is engageable by said fixed contact, said fixed contact and said resistive path being electrically connected to respective terminals on the casing and the angular position of the rotor relative to the fixed contact determining the resistance of the electrical circuit between the terminals.
 3. A switch as claimed in claim 1 wherein said abutment means is defined by an end wall of the casing and at least one flange integral with the casing and extending within the casing in space relation to said end wall, the rotor being disposed between the end wall and the flange.
 4. An electrical switch comprising a hollow casing, a plurality of fixed contacts mounted on the inner surface of the casing, a slider mounted for sliding movement within the casing and including a movable contact engageable with said fixed contacts, a plunger of noncircular cross section extending into the casing and journaled in an end wall of the casing for axial and angular movement relative to the casing the inner end of the plunger being rotatably coupled to said slider so that axial movement of the plunger causes sliding movement of the slider relative to the fixed contacts, a pair of abutments positioned within the casing adjacent said end wall, a printed circuit board positioned between the end wall and said abutments, said plunger extending through a corresponding noncircular hole in the printed circuit board so that said printed circuit board is rotated by angular movement of the plunger, said end wall and said abutments preventing axial movement of the printed circuit board with the plunger, a resistive electrically conductive path on said printed circuit board, a wiping contact carried by the casing and engaged with said resistive path, and a pair of terminals on the casing, one of said terminals being electrically connected to one end of said resistive path and the other terminal being electrically connected to said wiping contact so that the resistance of the electrical contact between said terminals is dependent upon the angular position of the printed circuit board relative to the wiping contact.
 5. A switch as claimed in claim 4 including resilient means for locating the printed circuit board in anyone of a plurality of predetermined angular positions relative to the casing. 